1. Field of the Invention
Exemplary embodiments of the invention relate to a display substrate and a method of manufacturing the display substrate. More particularly, exemplary embodiments of the invention relate to a display substrate including a polarization pattern and a method of manufacturing the display substrate.
2. Description of the Related Art
Generally, a liquid crystal display (“LCD”) device including liquid crystals further includes a polarization layer disposed on a rear surface and an upper surface of an LCD panel, so that the liquid crystals may function as a light shutter.
A polarization film is mainly used as the polarization layer. The polarization layer may include a polarization pattern. However, when a conductive polarization pattern including a striped shape is formed on a base substrate, the base substrate including the polarization pattern formed thereon may have a polarization function which reflects and polarizes an incident light. The striped-shape pattern has a longitudinal axis elongated in a first direction, and a transverse axis perpendicular to the longitudinal axis. When the polarization pattern formed on the base substrate has a nano-scale size, the polarization layer including the nano-scale sized polarization pattern has a polarization ratio near about 1100:1, so that the polarization layer may be replaced with a conventional polarization film. Here, the polarization ratio is defined by a ratio of a vertical polarization to a horizontal polarization.
A polarization layer including the polarization pattern is manufactured by the following process. A metal layer including aluminum (Al) and an insulation layer including a silicon oxide (SiOx) are deposited on a base substrate, and then the insulation layer is etched by using a photoresist, such that the etched insulation layer may function as a hard mask in a subsequent process. The metal layer is etched by using the hard mask to manufacture the polarization layer including the polarization pattern. However, the manufacturing method of the polarization layer described above may generate the following problems.
Generally, when an etching process is performed, an over-etching may be generated where about 30% more of a thin layer is undesirably removed. Thus, an etching mask should have a sufficient thickness as a margin against the over-etching.
However, when a thickness of the photoresist is not sufficient, a mask which is formed by a lower layer is blocked due to an over-etching process, so that the finally formed polarization pattern is not uniform. When a thickness of the photoresist is increased in order to prevent the above problem, a slant of the photoresist pattern may be generated. That is, a defect of the photoresist pattern itself may be generated.
Moreover, in a case that a metal layer has a stacked metal structure including titanium (Ti) and aluminum (Al), a reaction product material such as titanium fluoride (TiFx) polymer, etc., may be generated when an etching process using fluorine gas is performed. The titanium fluoride (TiFx) polymer may be formed by a fluorine gas used for etching an insulation layer which includes a silicon oxide (SiOx), and for etching titanium (Ti) formed under the insulation layer. The titanium fluoride (TiFx) polymer may disturb a subsequent patterning process used to form the polarization pattern.